Groups > linux.debian.user > #209352

Re: ssh local port forwarding stopped working

From	Bruce Halco <bruce@halcomp.com>
Newsgroups	linux.debian.user
Subject	Re: ssh local port forwarding stopped working
Date	2019-05-28 23:30 +0200
Message-ID	<y2RPs-7VD-3@gated-at.bofh.it> (permalink)
References	<y2OeR-5yy-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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I would test port status with

    nmap -P0 -p 22 <remote server public IP>


You want the response to be "open"

Bruce

On 5/28/19 12:17 PM, Gary Dale wrote:
> I'm running Debian/Testing on an AMD64 machine.
>
> I follow what I believe is a fairly conventional way of connecting to 
> remote machines. Firstly I establish an SSH tunnel using a command like:
>
>   ssh <remote server public IP> -L 5902:<remote workstation local 
> IP>:5900
>
> where the remote server public IP is that of the router (DD-WRT) with 
> port 22 forwarded to the local IP of a remote Debian/Stable server. 
> The remote workstation IPs are in the 192.168.1.* range. The SSH 
> connection works fine.
>
> Then I connect to localhost:5902 using a VNC viewer (tried a few).  
> I've been doing this for a decade with no significant problems.
>
> However I haven't been able to do this since at least yesterday 
> (previous remote login was a week ago. It worked). No matter which 
> remote machine I try to connect to, I never get to the password 
> prompt. Instead the connection attempt eventually attempt times out.
>
> I can log onto a KVM virtual machine running on the remote server 
> using the Virtual Machine Manager GUI. From there I can connect to the 
> other (real) machines using the Tight VNC viewer.
>
> Since I can connect to the remote workstations from the VM, the 
> problem cannot be with their service setup. And since the problem 
> isn't resolved by using a different VNC viewer from my local 
> workstation, the problem can't be the VNC client. This just leaves the 
> ssh tunnel - specifically the port forwarding - as the only common 
> element.
>

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ssh local port forwarding stopped working Gary Dale <gary@extremeground.com> - 2019-05-28 19:40 +0200
  Re: ssh local port forwarding stopped working Nicholas Geovanis <nickgeovanis@gmail.com> - 2019-05-28 20:00 +0200
  Re: ssh local port forwarding stopped working Bruce Halco <bruce@halcomp.com> - 2019-05-28 23:30 +0200

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